[A-CG37] Global Carbon Cycle Observation and Analysis

[ACG37-06] Assessment of future carbon cycle of CMIP5 and CMIP6 Models in tropical forests

*Takuto Taguchi¹, Kazuhito Ichii¹ (1.Center for Environmental Remote Sensing)

Keywords:CMIP5/CMIP6, Terrestrial carbon cycle, Tropical forests

Although tropical forests play an essential role in absorbing atmospheric CO2, there is a high degree of uncertainty regarding the processes and magnitude of absorption/emission and their future variability, and research has been conducted by integrating data from Earth System Models (ESM) and satellite observations. In this study, we focused on the effects of precipitation change during the dry season on the terrestrial carbon cycle, especially the relationship between GPP (Gross Primary Production) and precipitation change, and evaluated future water stress using the results reported by ESM.

Analyses of the output of 39 ESM models in the Coupled Model Intercomparison Project Phase 5 and 6 (CMIP5 and 6) showed that the CMIP5 MME (Multi Model Emsemble) showed a large variation in annual GPP among models in tropical forests, mainly in the Amazon region of South America. Although the variability was reduced in the CMIP6 MME, both models showed a decrease in GPP during the dry season from 1982 to 2005, which was not observed in the reference data.

The decline in dry-season GPP, which will be further advanced in the 2071-2100 projection, was more pronounced in areas with lower cumulative precipitation and higher mean annual temperatures during the dry season; the decline in GPP due to water stress, which confirmed in almost all of the CMIP5 MME, was ameliorated in the CMIP6 MME.